Parker Solar Probe and the Birth of the Solar Wind

This summer, humanity embarks on its first mission to touch the Sun: A spacecraft will be launched into the Sun’s outer atmosphere.

Facing several-million-degree Fahrenheit temperatures, NASA’s Parker Solar Probe — named after Eugene Parker, the University of Chicago physicist who first predicted the solar wind’s existence — will directly sample solar particles and magnetic fields in an attempt to resolve some of the most important questions facing the field of solar science today. Among those questions: What is the origin of the solar wind and how is it accelerated to speeds of up to 1.8 million miles per hour?

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The solar wind fills our entire solar system. When gusts of solar wind arrive at Earth, they can set off dazzling aurora — but also expose astronauts to radiation, interfere with satellite electronics, and disrupt communications signals like GPS and radio waves. The more we understand the fundamental processes that drive the solar wind, the more we can mitigate some of these effects.

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Credits: NASA/SDO

Dark coronal holes rotate into view in this image of the Sun in extreme ultraviolet light.

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Credits: NASA’s Goddard Space Flight Center/Lisa Poje/Genna Duberstein

Closed magnetic field lines loop back to the Sun to form helmet streamers, surrounded by open field lines that reach out into space, as depicted in this illustration.

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NASA’s Parker Solar Probe will be the first-ever mission to "touch" the sun. The spacecraft, about the size of a small car, will travel directly into the sun's atmosphere about 4 million miles from our star's surface. Launch is slated for summer 2018.

Parker Solar Probe’s heat shield, called the Thermal Protection System, is lifted and realigned with the spacecraft’s truss as engineers from the Johns Hopkins Applied Physics Lab prepare to install the eight-foot-diameter heat shield on July 27, 2018.

The eight-foot-diameter heat shield will safeguard everything within its umbra, the shadow it casts on the spacecraft. At Parker Solar Probe’s closest approach to the Sun, temperatures on the heat shield will reach nearly 2,500 degrees Fahrenheit, but the spacecraft and its instruments will be kept at a relatively comfortable temperature of about 85 degrees Fahrenheit.

The heat shield is made of two panels of superheated carbon-carbon composite sandwiching a lightweight 4.5-inch-thick carbon foam core. The Sun-facing side of the heat shield is also sprayed with a specially formulated white coating to reflect as much of the Sun’s energy away from the spacecraft as possible.

The heat shield itself weighs only about 160 pounds – here on Earth, the foam core is 97% air. Because Parker Solar Probe travels so fast – 430,000 miles per hour at its closest approach to the Sun, fast enough to travel from Philadelphia to Washington, D.C., in about one second – the shield and spacecraft have to be light to achieve the needed orbit.